Con Coughlin is the Telegraph's Defence Editor and a world-renowned expert on global security and terrorism issues. He is the author of several critically acclaimed books. His new book, Churchill's First War: Young Winston and the fight against the Taliban, is published by Macmillan in London and Thomas Dunne Books in New York. He appears regularly on radio and television in Britain and America.

The Taliban are getting increasingly desperate in their attacks on coalition forces

I have just returned from Afghanistan (a more detailed dispatch will shortly appear in the Telegraph) where I found the mood among British troops to be remarkably upbeat. Following the success of Operation Mostarak, the military campaign to drive Taliban insurgents from the strategically important Helmand town of Nad-e Ali, there is a clear sense among British and other Nato commanders that an important corner has been turned in the relentless campaign against the Taliban, and that the insurgents are on the run.

This would explain the increasingly desperate tactics the Taliban are employing, such as today's car bomb attacks in Kabul, to try to impress their supporters that they remain a force to be reckoned with.

But terror tactics alone are never going to determine the outcome of a conflict. If the Taliban want to prevail, they have to hold on to territory that they can use as a bargaining chip in any future negotiations on the future of the country.

But the fact that Nato forces – which have been immeasurably strengthened by the arrival of extra U.S. troops in support of Washington's military surge strategy – means the Taliban are gradually being forced to concede ground – in some cases even laying down their weapons. This means the only tactic open to them is to resort to car bomb attacks on heavily-populated civilian areas, which is an illustration of the Taliban's weakness, not its strength.